Radiant Heating

radiant heating: see heating.

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radiant heating

Heating system in which heat is transmitted by radiation from a heated surface. Radiant heating systems usually employ either electric-resistance wiring or hot-water heating pipes, which may embedded in the floor, ceiling, or walls. Panel heating is a form of radiant heating characterized by very large surfaces (typically an entire ceiling or floor) containing electrical conductors, hot-water pipes, or hot-air ducts. With many such systems there is no visible heating equipment in the room.

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radiant heating [′rād·ē·ənt ′hēd·iŋ]

(engineering)

Any system of space heating in which the heat-producing means is a surface that emits heat to the surroundings by radiation rather than by conduction or convection.

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Radiant heating

Any system of space heating in which the heat-producing means is a surface that emits heat to the surroundings by radiation rather than by conduction or convection. The surfaces may be radiators such as baseboard radiators or convectors, or they may be the panel surfaces of the space to be heated.

The heat derived from the Sun is radiant energy. Radiant rays pass through gases without warming them appreciably, but they increase the sensible temperature of liquid or solid objects upon which they impinge. The same principle applies to all forms of radiant-heating systems, except that convection currents are established in enclosed spaces and a portion of the space heating is produced by convection. Any radiant-heating system using a fluid heat conveyor may be employed as a cooling system by substituting cold water or other cold fluid. However, the technique is not practical on the scale required for comfort control of an occupied space.

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radiant heating

Heating which results from heat transmitted by radiation, as contrasted with heat transmitted by conduction or convection.

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Radiant Heating 

a type of heating in which heat is transmitted to the area being heated mainly by radiation and, to a substantially lesser extent, by convection. A characteristic feature of radiant heating is the arrangement of heaters under or in the ceiling of the area. In this case the radiant flux from the heaters propagates mainly downward through a diathermic medium (the air). It is received by the enclosing structures, particularly the floor. People on the premises also receive radiant heat from the heaters. Consequently, an advantage of radiant heating is that the ambient air temperature can be lower than when other types of heating are used. At the same time, the strong flux of radiant energy leads to the necessity of limiting the temperature of the heat-emitting surfaces.

Hot water (the most prevalent), steam, hot air, and electric power are used as the heat-transfer agents in radiant heating to supply the heating elements (for example, cable built into the enclosing structure). The heaters are often an integral part of the ceiling; in this case the floor of the next higher level is heated. To avoid discomfort for people in the area, the temperature of the floor surface should be no higher than 26°C. If the heaters are placed under a ceiling, the flat heat-emitting surfaces are called heating panels. Systems with such heaters are sometimes known as radiant panel systems. Systems of radiant heating exist in which the ceiling, which transmits heat to the premises, is heated by supplying hot air to the area from under the ceiling.

Systems using heating panels can be reset for radiant cooling in summer by passing cold water through the pipes that carry the heat-transfer agent in winter. In this case the temperature of the cooling surface exposed in the area must be kept above the dew point of the air, so that moisture does not condense on it. When heating panels are not used for summer cooling and the heat-transfer agent has a high temperature, it is good practice to arrange the panels vertically, particularly on the outer walls. This panel arrangement is most widely used in the USSR.

REFERENCE

Missenard, F.-A. Luchistoe otoplenie i okhlazhdenie. Moscow, 1961. (Translated from French.)

I. F. LIVCHAK